Structure of human nicotinamide/nicotinic acid mononucleotide adenylyltransferase. Basis for the dual substrate specificity and activation of the oncolytic agent tiazofurin

Tianjun Zhou, Oleg Kurnasov, Diana R. Tomchick, Derk D. Binns, Nick V. Grishin, Victor E. Marquez, Andrei L. Osterman, Hong Zhang

Research output: Contribution to journalArticle

66 Scopus citations

Abstract

Nicotinamide/nicotinate mononucleotide (NMN/NaMN)adenylyltransferase (NMNAT) is an indispensable enzyme in the biosynthesis of NAD+ and NADP+. Human NMNAT displays unique dual substrate specificity toward both NMN and NaMN, thus flexible in participating in both de novo and salvage pathways of NAD synthesis. Human NMNAT also catalyzes the ratelimiting step of the metabolic conversion of the anticancer agent tiazofurin to its active form tiazofurin adenine dinucleotide (TAD). The tiazofurin resistance is mainly associated with the low NMNAT activity in the cell. We have solved the crystal structures of human NMNAT in complex with NAD, deamido-NAD, and a non-hydrolyzable TAD analogue β-CH2-TAD. These complex structures delineate the broad substrate specificity of the enzyme toward both NMN and NaMN and reveal the structural mechanism for adenylation of tiazofurin nucleotide. The crystal structure of human NMNAT also shows that it forms a barrel-like hexamer with the predicted nuclear localization signal sequence located on the outside surface of the barrel, supporting its functional role of interacting with the nuclear transporting proteins. The results from the analytical ultracentrifugation studies are consistent with the formation of a hexamer in solution under certain conditions.

Original languageEnglish (US)
Pages (from-to)13148-13154
Number of pages7
JournalJournal of Biological Chemistry
Volume277
Issue number15
DOIs
StatePublished - Apr 12 2002

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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